1. Field of the Invention
The present invention relates to the field of semiconductor processing and more specifically to a method and apparatus for integrating a metal-nitride film in a semiconductor device.
2. Discussion of Related Art
Integrated circuits are made up of literally millions of active and passive devices such as transistors, capacitors and resistors n order to provide more computational power and/or more storage capability in an integrated circuit, device features are reduced or scaled down in order to provide higher packing density of devices. An important feature to enable scaling of devices is the ability to form high quality, high dielectric constant films for capacitor and gate dielectrics.
Metal-oxides (ceramics) films, such as tantalum pentaoxide (TaO5) and titanium oxide (TiO2) have been proposed to fill the need for high dielectric constant films. In some processes, metal nitride barrier layers such as titanium-nitride (TiN) and tantalum-nitride (TaN) are used to separate metal oxide dielectrics from metals films, such as tungsten, used to form capacitors and gate electrodes. A barrier layer is used to prevent metal atoms in the capacitor or gate electrode from stealing oxygen atoms from the metal oxide dielectric and causing vacancies therein which can lead to high leakage currents. In other processes metal nitride films form capacitor or gate electrode. Unfortunately, however, present methods of forming metal nitrides, such as thermal chemical vapor deposition, have been found to alter metal-oxide dielectric film qualities and lead to a degradation in performance and reliability of the fabricated devices.
Thus, what is desired is a method and for forming a high quality low resistance metal-nitride film onto a high dielectric constant metal oxide dielectric in a semiconductor device.
The present invention describes a method of processing a substrate. According to the present invention a dielectric layer is formed on the substrate. The dielectric layer is then exposed in a first chamber to activated nitrogen atoms formed in a second chamber to form a nitrogen passivated dielectric layer. A metal nitride film is then formed on the nitrogen passivated dielectric layer.